On Thu, Aug 24, 2023 at 11:00 PM James Almer <jamr...@gmail.com> wrote:
> On 8/24/2023 6:52 AM, Paul B Mahol wrote:
> > +static int osq_receive_frame(AVCodecContext *avctx, AVFrame *frame)
> > +{
> > + OSQContext *s = avctx->priv_data;
> > + GetBitContext *gb = &s->gb;
> > + int ret, n;
> > +
> > + while (s->bitstream_size < s->max_framesize) {
> > + int size;
> > +
> > + if (!s->pkt->data) {
> > + ret = ff_decode_get_packet(avctx, s->pkt);
> > + if (ret == AVERROR_EOF && s->bitstream_size > 0)
> > + break;
> > + if (ret < 0)
> > + return ret;
> > + }
> > +
> > + size = FFMIN(s->pkt->size - s->pkt_offset, s->max_framesize -
> s->bitstream_size);
> > + memcpy(s->bitstream + s->bitstream_size, s->pkt->data +
> s->pkt_offset, size);
> > + s->bitstream_size += size;
> > + s->pkt_offset += size;
> > +
> > + if (s->pkt_offset == s->pkt->size) {
> > + av_packet_unref(s->pkt);
> > + s->pkt_offset = 0;
> > + }
>
> This looks like you're assembling a packet of max_framesize bytes. You
> should instead do that in a parser, and ensure here that the packets fed
> to this decoder are <= max_framesize.
>
> > + }
> > +
> > + frame->nb_samples = FFMIN(s->frame_samples, s->nb_samples);
> > + if (frame->nb_samples <= 0)
> > + return AVERROR_EOF;
> > +
> > + if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
> > + goto fail;
> > +
> > + if ((ret = init_get_bits8(gb, s->bitstream, s->bitstream_size)) < 0)
> > + goto fail;
> > +
> > + if ((ret = osq_decode_block(avctx, frame)) < 0)
> > + goto fail;
> > +
> > + s->nb_samples -= frame->nb_samples;
> > +
> > + n = get_bits_count(gb) / 8;
> > + if (n > s->bitstream_size) {
> > + ret = AVERROR_INVALIDDATA;
> > + goto fail;
> > + }
> > +
> > + memmove(s->bitstream, &s->bitstream[n], s->bitstream_size - n);
> > + s->bitstream_size -= n;
> > +
> > + return 0;
> > +
> > +fail:
> > + s->bitstream_size = 0;
> > + s->pkt_offset = 0;
> > + av_packet_unref(s->pkt);
> > +
> > + return ret;
> > +}
> > +
> > +const AVInputFormat ff_osq_demuxer = {
> > + .name = "osq",
> > + .long_name = NULL_IF_CONFIG_SMALL("raw OSQ"),
> > + .read_probe = osq_probe,
> > + .read_header = osq_read_header,
> > + .read_packet = ff_raw_read_partial_packet,
>
> Instead of sending an arbitrarily sized packet (1024 bytes as of now),
> you should set codecpar->frame_size and propagate packets with that
> amount of bytes instead.
> A parser is still needed, though, for non seekable input (a pipe). And
> in case the decoder is fed with non lavf input.
>
Format is not seekable, packet sizes are nowhere stored in .osq files.
Think of this format like APAC/BONK/WAVARC but just no need to keep unused
bits from previous decoded data/packet.
With this fact, parser makes no sense to do.
> > + .extensions = "osq",
> > + .flags = AVFMT_NOBINSEARCH | AVFMT_NOGENSEARCH |
> AVFMT_NO_BYTE_SEEK | AVFMT_NOTIMESTAMPS,
> > + .raw_codec_id = AV_CODEC_ID_OSQ,
> > + .priv_data_size = sizeof(FFRawDemuxerContext),
> > + .priv_class = &ff_raw_demuxer_class,
> > +};
>
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